It is well known that contact lenses can be used to improve vision. Various contact lenses have been commercially produced for many years. Hydrogel contact lenses are very popular today. These lenses are formed from hydrophilic polymers and copolymers containing repeating units from hydroxyethylmethylacrylate (HEMA). Of these contact lenses formed from copolymers of HEMA and methacrylic acid, are among the most comfortable, and have the lowest rate of adverse events. Contact lenses formed from copolymers of HEMA and MAA, such ACUVUE contact lenses, display substantial amounts of lysozyme uptake (greater than 500 μg) and retain a majority of the uptaken proteins in their native state. However, hydrogel contact lenses generally have oxygen permeabilities that are less than about 30.
Contact lenses made from silicone hydrogels have been disclosed. These silicone hydrogel lenses have oxygen permeabilities greater than about 60, and many provide reduced levels of hypoxia compared to conventional hydrogel contact lenses. Unfortunately, attempts to add anionic components to silicone hydrogels in the past have produced contact lenses which are not hydrolytically stable and display moduli which increase when exposed to water and heat. Also, while adding ionicity to silicone hydrogels has increased lysozyme uptake, it has also often increased uptake of positively charged components from contact lens multipurpose solutions. One such component is PQ1, a polyquaternium disinfecting compound. Also, many silicone hydrogels have higher than desired contact angles.